Rapid, low-loss and effective red tilapia cold stress evaluation system and evaluation method

Abstract

The invention discloses a rapid, low-loss and effective red tilapia cold stress evaluation system and evaluation method, and belongs to the technical field of aquaculture, the evaluation system comprises an index layer, a method layer and an application layer, the index layer comprises a behavior index, a body color index, a blood index and a tail fin pigment cell index; according to the method layer, a control group and a monitoring group are set, index values are measured respectively, the measured value of the control group serves as a standard value, and the differentiation degree of the monitoring group and the control group is judged through an evaluation model. The application layer is used for regulating and controlling a breeding strategy according to the differentiation degree of the monitoring group and the control group; according to the method, a four-dimensional quantitative evaluation system is constructed, and a grading early warning mechanism for the red tilapia breeding state is realized through a differentiation degree value algorithm; according to the method, the state of the tilapia can be pre-judged, so that a feeder can timely adjust a breeding strategy, and the death problem caused by cold stress or acute cold stress in the breeding process is reduced to the maximum extent.

Description

Technical Field

[0001] The invention relates to the technical field of aquaculture, and in particular to a rapid, low-loss and effective cold stress evaluation system and evaluation method for red tilapia. Background Art

[0002] Red tilapia (Oreochromis spp.) is a globally important commercial fish species, generally believed to be a superior species bred through multiple generations of crossbreeding of a mutant red Mozambique tilapia (O. mossambicus) with other tilapia species, such as the Nile tilapia (O. niloticus). Due to its vibrant color, lack of a melanin-like membrane in the abdominal cavity, strong adaptability, refreshing taste, and high market value, its cultivation area in my country has been continuously expanding in recent years, creating a significant market opportunity. However, cold stress during its wintering period has been a bottleneck hindering the rapid development of the industry. This cold stress is primarily manifested in a drop in water temperature, resulting in a decrease in the red tilapia's immune and antioxidant capacity, a darkening of its apparent color, and even a blackening of the entire pond, leading to mass mortality. Consequently, in most parts of my country, red tilapia must be moved to greenhouses for wintering, increasing the difficulty of aquaculture.

[0003] In recent years, extreme weather events such as cold snaps, driven by global climate change, have become more frequent. Traditionally, determining whether fish are experiencing stress requires analyzing changes in behavior and appetite, combined with post-mortem testing for various indicators such as oxidative stress. This severely limits the size of research samples and hinders genetic improvement of fish stress resistance. Therefore, a rapid, non-lethal (low-damage), and effective evaluation system and method for cold stress in fish is urgently needed. This would represent an innovative approach to stress identification for fish such as red tilapia. Summary of the Invention

[0004] The present invention aims to provide a rapid, low-loss, and effective cold stress evaluation system and method for red tilapia, so as to solve the problems existing in the above-mentioned prior art. The system can timely, effectively, and quickly evaluate the status of red tilapia and take corresponding breeding measures to reduce cold stress, especially acute cold stress, during the wintering period of red tilapia.

[0005] To achieve the above object, the present invention provides the following solutions:

[0006] The present invention provides a rapid, low-loss and effective cold stress evaluation system for red tilapia. The key lies in that the evaluation system comprises an indicator layer, a method layer and an application layer. The indicator layer comprises behavioral indicators, body color indicators, blood indicators and tail fin pigment cell indicators; the method layer is to set up a control group and a monitoring group, and measure the indicator values ​​respectively, take the measured values ​​of the control group as the standard value, and use the evaluation model to judge the degree of differentiation between the monitoring group and the control group; the application layer is to regulate the breeding strategy according to the degree of differentiation between the monitoring group and the control group.

[0007] Specifically, the above-mentioned behavioral indicators include the fish's feeding conditions, swimming status and balance status; the above-mentioned body color indicators include the L* value and b* value of the abdominal skin; the above-mentioned blood indicators include total cholesterol, total protein, total bilirubin, urea, epinephrine, blood sugar, alkaline phosphatase, triglycerides, alanine aminotransferase and aspartate aminotransferase in the blood; the above-mentioned tail fin pigment cell indicators include the number, aggregation status and red body color status of the tail fin pigment cells.

[0008] Specifically, the L* value is the lightness, which indicates the brightness or lightness of the color; the b* value is the yellow-blue axis, which indicates the position of the color on the yellow-blue spectrum axis.

[0009] It should be noted that the above-mentioned control group is red tilapia whose living water temperature is maintained at 20°C or above.

[0010] Furthermore, the steps of establishing the above evaluation model include:

[0011] S1. The body color index and blood index were compared with the corresponding indexes of the control group. If P < 0.05, it was considered to be significantly different and scored 1 point. Otherwise, it was considered to be non-significant and scored 0 point.

[0012] S2. Quantify behavioral indicators and tail fin pigment cell indicators and record the scores;

[0013] S3. Weight distribution: The weight coefficient of behavioral indicators is 0.3, the weight coefficient of body color indicators is 0.25, the weight coefficient of blood indicators is 0.3, and the weight coefficient of tail fin pigment cell indicators is 0.15;

[0014] S4, get the formula 1 of the differentiation degree value,

[0015] Differentiation degree value = (behavioral index score × 0.3 + body color index score × 0.25 + blood index score × 0.3 + tail fin pigment cell index score × 0.15) × 20.62 (Equation 1).

[0016] Furthermore, behavioral indicators can be quantified in the following ways:

[0017] Case 1: No abnormal behavior, judged as normal, 0 points;

[0018] Case 2: Decreased food intake and slower swimming speed are considered mild abnormalities and are scored 1 point;

[0019] Case 3: The fish has a significant decrease in food intake, sinks to the bottom and moves less, which is considered as moderate abnormality and is scored 2 points;

[0020] Case 4: Stopping eating and losing body balance are considered severe abnormalities and are scored 3 points.

[0021] Furthermore, the quantification method of tail fin pigment cell index is:

[0022] Case 1: Erythrocytes are not aggregated and are characteristically red, which is considered normal and scored 0 points;

[0023] Case 2: Red pigment cells decrease and aggregate, red body color decreases, and melanocytes are absent. This is considered mild abnormality and is scored 1 point.

[0024] Case 3: The red pigment cells decrease and aggregate, the red body color decreases, and melanocytes appear, which is considered moderate abnormality and scored 2 points;

[0025] Case 4: The number of red pigment cells decreases and aggregates, the red body color fades, melanocytes appear and the black body color deepens. This is judged as a severe abnormality and is scored 3 points.

[0026] Finally, the breeding strategy is regulated based on the differentiation degree value, including:

[0027] 0<differentiation degree value≤20, normal state, normal breeding;

[0028] 20<Differentiation value≤50, indicating the occurrence of cold stress compensation period, the water temperature should be raised to 18℃ and vitamin C should be added to the feed;

[0029] 50<differentiation value≤70, indicating cold stress problem, isolation and warming, and injection of dexamethasone;

[0030] 70<differentiation value≤100, indicating acute cold stress problem, the red tilapia were transferred to a 25℃ recovery tank and injected with dexamethasone.

[0031] The key to a rapid, low-loss, and effective cold stress evaluation method for red tilapia is to use the above-mentioned evaluation system to evaluate the cold stress of red tilapia. The specific steps are:

[0032] A control group and a monitoring group were set up, and the behavioral indicators, body color indicators, blood indicators and tail fin pigment cell indicators of red tilapia in the control group and the monitoring group were measured respectively;

[0033] The measured value of the control group was used as the standard value, and the evaluation model was used to judge the degree of differentiation between the monitoring group and the control group, and the differentiation degree value was calculated;

[0034] According to the range of differentiation degree values, the status of red tilapia in the monitoring group is determined and the breeding strategy is adjusted.

[0035] Specifically, the states of red tilapia in the monitoring group include normal state, cold stress compensation state, cold stress state and acute cold stress state.

[0036] The present invention discloses the following technical effects:

[0037] This invention establishes a four-dimensional quantitative evaluation system, using a differentiated degree value algorithm to implement a graded early warning mechanism for the breeding status of red tilapia. This system can predict the status of tilapia within six hours and provide early warning of cold stress or acute cold stress in red tilapia, allowing farmers to promptly adjust their breeding strategies and minimize mortality caused by cold stress or acute cold stress during the breeding process.

[0038] The present invention greatly reduces the misjudgment rate and improves the accuracy of prediction by means of multi-indicator mutual verification. The application of the present invention not only avoids the lag and excessive intervention of state judgment in traditional breeding methods, but also can accurately regulate the feeding strategy, such as timely taking drug treatment or heat preservation strategies, reducing winter losses while also reducing heating consumption, saving material and manpower such as drugs, and improving the economic benefits of red tilapia breeding. The present invention converts complex physiological responses into an operational digital decision-making system, constructs a fast, low-loss, and efficient evaluation system and evaluation method for fish cold stress status, and provides an industrial application paradigm for fish health management. BRIEF DESCRIPTION OF THE DRAWINGS

[0039] In order to more clearly illustrate the embodiments of the present invention or the technical solutions in the prior art, the following briefly introduces the drawings required for use in the embodiments. Obviously, the drawings described below are only some embodiments of the present invention. For ordinary technicians in this field, other drawings can be obtained based on these drawings without paying any creative work.

[0040] Figure 1 This is a photo of the red tilapia "Zhongheng No. 1";

[0041] Figure 2 This is a photo of the first quantification of pigment cell indicators in the tail fin of red tilapia;

[0042] Figure 3 This is a photo of the second quantification of pigment cell indicators in the tail fin of red tilapia;

[0043] Figure 4 This is a photo of the third quantification of pigment cell indicators in the tail fin of red tilapia. DETAILED DESCRIPTION

[0044] Various exemplary embodiments of the present invention will now be described in detail. This detailed description should not be considered as limiting the present invention, but rather as a more detailed description of certain aspects, features, and embodiments of the present invention.

[0045] It should be understood that the terms described herein are intended only to describe particular embodiments and are not intended to limit the present invention. In addition, for numerical ranges herein, it should be understood that each intermediate value between the upper and lower limits of the range is also specifically disclosed. The intermediate value within any stated value or stated range, and each smaller range between any other stated value or intermediate value within the stated range, is also encompassed within the present invention. The upper and lower limits of these smaller ranges may be independently included or excluded within the scope.

[0046] Unless otherwise indicated, all technical and scientific terms used herein have the same meaning as commonly understood by those skilled in the art. Although only preferred methods and materials are described herein, any methods and materials similar or equivalent to those described herein may also be used in the practice or testing of the present invention. All documents mentioned in this specification are incorporated by reference to disclose and describe the methods and / or materials associated with the documents. In the event of any conflict with any incorporated document, the contents of this specification shall prevail.

[0047] It will be apparent to those skilled in the art that various modifications and variations may be made to the specific embodiments described herein without departing from the scope or spirit of the invention. Other embodiments will be apparent to those skilled in the art from the description of the invention. The description and examples are intended to be exemplary only.

[0048] The words “include,” “including,” “have,” “contain,” etc. used in this document are open-ended terms, meaning including but not limited to.

[0049] In Examples 1 and 2, a new aquatic species, red tilapia "Zhongheng No. 1", was selected as the experimental subject. The red tilapia "Zhongheng No. 1" was bred with the Malaysian strain of red tilapia as the basic breeding population, with body color and growth rate as the main indicators, using group breeding technology, and was bred for 5 consecutive generations. The body color of the red tilapia "Zhongheng No. 1" is a stable and consistent pink, see Figure 1 At the beginning of the experiment, all the fish were kept in a cylindrical fiberglass tank with a diameter of 150 cm and a depth of 120 cm.

[0050] Example 1

[0051] At the beginning of the experiment, 80 healthy and vigorous fish were randomly selected. The initial weight of the selected red tilapia was 72.71 g ± 1.32 g. They were randomly divided into two groups, 40 in each group, to obtain monitoring group 1 and control group 1.

[0052] The experimental period was the wintering period, with room temperature below 6°C. The water temperature in the control group 1 was maintained at around 20°C, while the water temperature in the monitoring group 1 decreased by 2°C per day, from 20°C to 8°C.

[0053] During the experiment, the temperature controller of monitoring group 1 was adjusted to lower by 2°C at 8 am every day. During the experiment, monitoring group 1 and control group 1 used the same commercial fish feed and were fed twice a day until the day before sampling.

[0054] Each aquarium was aerated for 24 h per day and had a light intensity of 12 D:12 L. During the experiment, behavioral indicators of red tilapia, including feeding, swimming, and balance, were observed and recorded daily.

[0055] At the end of the experiment, fish in monitoring group 1 and control group 1 were sampled.

[0056] Six red tilapia were randomly selected from monitoring group 1 as test samples, and six red tilapia were randomly selected from control group 1 as control samples. The results are as follows:

[0057] 1. Observation and quantification of behavioral indicators:

[0058] During the experiment, it was found that some red tilapia in monitoring group 1 stopped feeding when the water temperature was below 10℃, and sank to the bottom of the water and gradually lost balance when the water temperature was below 9℃. No fish died during the experiment.

[0059] The specific method for quantifying behavioral indicators is:

[0060] Case 1: No abnormal behavior, judged as normal, 0 points;

[0061] Case 2: Decreased food intake and slower swimming speed are considered mild abnormalities and are scored 1 point;

[0062] Case 3: The fish has a significant decrease in food intake, sinks to the bottom and moves less, which is considered as moderate abnormality and is scored 2 points;

[0063] Case 4: Stopping eating and losing body balance are considered severe abnormalities and are scored 3 points.

[0064] At the end of the experiment, four of the six red tilapia in monitoring group 1 exhibited condition three, resulting in a behavioral index score of 2, and two exhibited condition two, resulting in a behavioral index score of 1. Taking the average, the behavioral index score for monitoring group 1 was 1.67. All six red tilapia in control group 1 exhibited condition one.

[0065] 2. Body color index test results:

[0066] A ColorQuest XE (Hunterlab, USA) colorimeter was used to measure the L*, a*, and b* values ​​of the fish back and abdomen skin. The L* value represents the brightness or lightness of the color; the a* value represents the red-green axis, representing the position of the color on the red-green spectrum; and the b* value represents the yellow-blue axis, representing the position of the color on the yellow-blue spectrum.

[0067] The results are shown in Table 1.

[0068] Table 1: Test results of body color index of red tilapia in monitoring group 1 and control group 1

[0069]

[0070] Note: * indicates significant level (P<0.05)

[0071] As can be seen from the results in Table 1, based on the quantification of the body color index, when the L* value of the abdominal skin of the red tilapia in monitoring group 1 is significantly lower than that of the control group 1, 1 point is scored; when the b* value of the abdominal skin of the red tilapia in monitoring group 1 is significantly lower than that of the control group 1, 1 point is scored. In this embodiment, the body color index score of the red tilapia in monitoring group 1 is 1 point.

[0072] 3. Blood index test results

[0073] Blood was collected from red tilapia using the tail vein method. Serum samples were obtained after centrifugation at 4°C (3000 rpm, 15 min). Routine blood tests were performed using a Mindray BS-400Q2080 biochemical analyzer (Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China). The results are shown in Table 2.

[0074] Table 2: Blood routine test results of red tilapia in monitoring group 1 and control group 1

[0075] Indicator (unit) Monitoring Group 1 Control group 1 Significance Aspartate aminotransferase (AST) (U / L) 648.43±18.88 554.13±53.69 Alkaline phosphatase (ALP) (U / L) 14.60±0.12 27.45±0.66 ** Total bilirubin TBIL (μmol / L) 6.63±0.63 11.83±0.64 ** Total protein TP (g / L) 34.64±1.94 32.56±0.54 Albumin ALB (g / L) 14.02±0.88 13.36±0.23 Urea (mmol / L) 0.96±0.08 0.59±0.08 * Total cholesterol TC (mmol / L) 4.54±0.05 5.34±0.30 * Triglyceride TG (mmol / L) 1.95±0.09 1.68±0.16 Creatinine CREA (μmol / L) 13.93±1.38 16.93±0.82 Glucose GLU (mmol / L) 10.47±0.22 8.23±0.41 ** Thyroxine T4 (ng / L) 13.07±0.38 13.27±0.61 Cortisol (ng / L) 94.75±1.86 94.45±2.95 Epinephrine EPI (ng / L) 9.47±0.52 8.61±0.26 Norepinephrine (NE) (ng / L) 74.33±1.15 64.95±4.10 * Catecholamine CA (ng / L) 98.65±5.35 92.08±5.57

[0076] Note: * indicates significant level (P<0.05), ** indicates extremely significant difference (P<0.01).

[0077] As shown in Table 2, the urea (UREA), norepinephrine (NE), and blood glucose (GLU) levels in the serum of red tilapia in monitoring group 1 were significantly higher than those in control group 1 (P < 0.05); the alkaline phosphatase (ALP), total bilirubin (TBIL), and total cholesterol (TC) levels were significantly lower than those in control group 1 (P < 0.05). There were no significant differences in other indicators between the two groups.

[0078] According to the evaluation system of the present invention, a total of six blood indicators, including total cholesterol (TC), total bilirubin (TBIL), urea (UREA), norepinephrine (NE), blood glucose (GLU) and alkaline phosphatase (ALP), were significantly different from those in the control group 1, and the blood index score of red tilapia in the monitoring group 1 was 6 points.

[0079] 4. Observation and quantification of tail fin pigment cell indicators

[0080] A small piece of the upper right tail fin was collected, and the number and characteristics of the tail fin pigment cells were observed under a microscope to determine the tail fin pigment cell indicators.

[0081] According to the evaluation system of the present invention, the quantification method of the tail fin pigment cell index is:

[0082] Case 1: Erythrocytes are not aggregated and are characteristically red, which is considered normal and scored 0 points;

[0083] Case 2: Red pigment cells decrease and aggregate, red body color decreases, and melanocytes are absent. This is considered mild abnormality and is scored 1 point.

[0084] Case 3: The red pigment cells decrease and aggregate, the red body color decreases, and melanocytes appear, which is considered moderate abnormality and scored 2 points;

[0085] Case 4: The number of red pigment cells decreases and aggregates, the red body color fades, melanocytes appear and the black body color deepens. This is judged as a severe abnormality and is scored 3 points.

[0086] At the end of the experiment, three of the six red tilapia in monitoring group 1 exhibited condition 2, resulting in a behavioral index score of 1, and three exhibited condition 3, resulting in a behavioral index score of 2. Taking the average, the tail fin pigment cell index score for monitoring group 1 was 1.5. All six red tilapia in control group 1 exhibited condition 1.

[0087] The test and quantification results of various indicators in this embodiment are shown in Table 3.

[0088] Table 3: Test and quantification results of various indicators of monitoring group 1

[0089]

[0090]

[0091] According to Formula 1, the differentiation degree value is calculated.

[0092] Formula 1 is as follows:

[0093] The degree of differentiation is calculated as (behavioral index score × 0.3 + body color index score × 0.25 + blood index score × 0.3 + tail fin pigment cell index score × 0.15) × 20.62. In formula 1, 20.62 is used as a constant coefficient to normalize the score to a percentage. Therefore, after weighting, the full score is 4.85, and 100 ÷ 4.85 ≈ 20.62.

[0094] The differentiation degree value of monitoring group 1 is 57.24. The breeding strategy is regulated based on the differentiation degree value, including:

[0095] 0<differentiation degree value≤20, normal state, normal breeding;

[0096] 20<Differentiation value≤50, indicating the occurrence of cold stress compensation period, the water temperature should be raised to 18℃ and vitamin C should be added to the feed;

[0097] 50<differentiation value≤70, indicating cold stress problem, isolation and warming, and injection of dexamethasone;

[0098] 70<differentiation value≤100, indicating acute cold stress problem, the red tilapia were transferred to a 25℃ recovery tank and injected with dexamethasone.

[0099] Based on the above judgment conditions, it can be seen that monitoring group 1 has a cold stress problem. Monitoring group 1 should be isolated, warmed up, and injected with dexamethasone.

[0100] Example 2

[0101] At the beginning of the experiment, 80 healthy and vigorous red tilapia were randomly selected with an initial body weight of 45.07 g ± 0.27 g. They were randomly divided into two groups of 40 fish each, obtaining monitoring group 2 and control group 2.

[0102] The experimental period was the wintering period, with room temperatures below 6°C. The water temperature in control group 2 was maintained at approximately 21°C, while the water temperature in monitoring group 2 was decreased by 1°C every half hour until it reached 10°C. No feeding was performed during the experimental period until sampling.

[0103] Each aquarium was aerated for 24 hours per day and had a light intensity of 12 days and 12 hours per day. During the experiment, the behavioral indicators of red tilapia, including feeding, swimming status, and balance status, were observed and recorded.

[0104] At the end of the experiment, fish in monitoring group 2 and control group 2 were sampled.

[0105] Six red tilapia were randomly selected from monitoring group 2 as test samples, and six were randomly selected from control group 2 as control samples. The results are as follows:

[0106] 1. Observation and quantification of behavioral indicators:

[0107] During the experiment, it was found that as the temperature dropped, some red tilapia in Monitoring Group 2 gradually slowed down, until at 9°C the fish sank to the bottom and essentially stopped swimming. No fish died during the experiment.

[0108] The specific method for quantifying behavioral indicators is:

[0109] Case 1: No abnormal behavior, judged as normal, 0 points;

[0110] Case 2: Decreased food intake and slower swimming speed are considered mild abnormalities and are scored 1 point;

[0111] Case 3: The fish has a significant decrease in food intake, sinks to the bottom and moves less, which is considered as moderate abnormality and is scored 2 points;

[0112] Case 4: Stopping eating and losing body balance are considered severe abnormalities and are scored 3 points.

[0113] At the end of the experiment, five of the six red tilapia in Monitoring Group 2 exhibited Situation 4, resulting in a behavioral index score of 3, and one exhibited Situation 3, resulting in a behavioral index score of 2. Taking the average, the behavioral index score for Monitoring Group 2 was 2.83. All six red tilapia in Control Group 2 exhibited Situation 1.

[0114] 2. Body color index test results:

[0115] The L* value, a* value, and b* value of the fish back and abdomen skin were measured using a ColorQuest XE (Hunterlab, USA) colorimeter. The results are shown in Table 4.

[0116] Table 4: Test results of body color index of red tilapia in monitoring group 2 and control group 2

[0117]

[0118]

[0119] Note: * indicates significant level (P<0.05)

[0120] As can be seen from the results in Table 4, according to the quantification of body color indicators, when the L* value of the abdominal skin of red tilapia in monitoring group 2 was significantly lower than that in control group 2, 1 point was scored; when the b* value of the abdominal skin of red tilapia in monitoring group 2 was significantly lower than that in control group 2, 1 point was scored.

[0121] In this embodiment, the body color index score of the red tilapia of monitoring group 2 is 2 points.

[0122] 3. Blood index test results

[0123] Blood was collected from red tilapia using the tail vein method. Serum samples were obtained after centrifugation at 4°C (3000 rpm, 15 min). Routine blood tests were performed using a Mindray BS-400Q2080 biochemical analyzer (Mindray Bio-Medical Electronics Co., Ltd., Shenzhen, China). The results are shown in Table 5.

[0124] Table 5: Blood routine test results of red tilapia in monitoring group 2 and control group 2

[0125]

[0126]

[0127] Note: * indicates significant level (P<0.05), ** indicates extremely significant difference (P<0.01).

[0128] As shown in Table 5, the blood glucose (GLU), total protein (TP), and triglyceride (TG) levels in the serum of red tilapia in monitoring group 2 were significantly higher than those in control group 2 (P < 0.05); the alkaline phosphatase (ALP), total bilirubin (TBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST) levels were significantly lower than those in control group 2 (P < 0.05). There were no significant differences in other indicators between the two groups.

[0129] According to the evaluation system of the present invention, a total of seven blood indicators, including blood glucose (GLU), total protein (TP), triglyceride (TG), alkaline phosphatase (ALP), total bilirubin (TBIL), alanine aminotransferase (ALT), and aspartate aminotransferase (AST), were significantly different from those in the control group 2, and the blood index score of red tilapia in the monitoring group 2 was 7 points.

[0130] 4. Observation and quantification of tail fin pigment cell indicators

[0131] A small piece of the upper right tail fin was collected, and the number and characteristics of the tail fin pigment cells were observed under a microscope to determine the tail fin pigment cell indicators.

[0132] According to the evaluation system of the present invention, the quantification method of the tail fin pigment cell index is:

[0133] Case 1: Erythrocytes are not aggregated and are characteristically red, which is considered normal and scored 0 points;

[0134] Case 2: Red pigment cells decrease and aggregate, red body color decreases, and melanocytes are absent. This is considered mild abnormality and is scored 1 point.

[0135] Case 3: The red pigment cells decrease and aggregate, the red body color decreases, and melanocytes appear, which is considered moderate abnormality and scored 2 points;

[0136] Case 4: The number of red pigment cells decreases and aggregates, the red body color fades, melanocytes appear and the black body color deepens. This is judged as a severe abnormality and is scored 3 points.

[0137] At the end of the experiment, five of the six red tilapia in Monitoring Group 2 exhibited Condition 3, resulting in a behavioral index score of 2, while one exhibited Condition 2, resulting in a behavioral index score of 1. Taking the average, the tail fin pigment cell index score for Monitoring Group 2 was 1.83. All six red tilapia in Control Group 2 exhibited Condition 1.

[0138] The test and quantification results of various indicators in this embodiment are shown in Table 6.

[0139] Table 6: Testing and quantification results of various indicators of monitoring group 2

[0140]

[0141] The differentiation degree value is calculated according to Formula 1, which is described in Example 1.

[0142] The differentiation degree value of monitoring group 2 is 76.8. The breeding strategy is regulated based on the differentiation degree value, including:

[0143] 0<differentiation degree value≤20, normal state, normal breeding;

[0144] 20<Differentiation value≤50, indicating the occurrence of cold stress compensation period, the water temperature should be raised to 18℃ and vitamin C should be added to the feed;

[0145] 50<differentiation value≤70, indicating cold stress problem, isolation and warming, and injection of dexamethasone;

[0146] 70<differentiation value≤100, indicating acute cold stress problem, the red tilapia were transferred to a 25℃ recovery tank and injected with dexamethasone.

[0147] Based on the above judgment conditions, it can be seen that monitoring group 2 has acute cold stress problem. The red tilapia in monitoring group 2 should be immediately transferred to a 25℃ recovery pool and injected with dexamethasone.

[0148] The embodiments described above are merely descriptions of preferred embodiments of the present invention and are not intended to limit the scope of the present invention. Without departing from the spirit of the present invention, various modifications and improvements made to the technical solutions of the present invention by persons skilled in the art should fall within the scope of protection defined by the claims of the present invention.

Claims

1. A rapid, low-loss, and effective cold stress evaluation system for red tilapia, characterized by: The evaluation system includes an indicator layer, a method layer and an application layer. The indicator layer includes behavioral indicators, body color indicators, blood indicators and tail fin pigment cell indicators; the method layer is to set up a control group and a monitoring group, and measure the indicator values ​​respectively, use the measured values ​​of the control group as the standard value, and use the evaluation model to judge the degree of differentiation between the monitoring group and the control group; the application layer is to regulate the breeding strategy according to the degree of differentiation between the monitoring group and the control group.

2. The rapid, low-loss, and effective cold stress evaluation system for red tilapia as claimed in claim 1, wherein: The behavioral indicators include the fish's feeding conditions, swimming status and balance status; the body color indicators include the L* value and b* value of the abdominal skin; the blood indicators include total cholesterol, total protein, total bilirubin, urea, epinephrine, blood sugar, alkaline phosphatase, triglycerides, alanine aminotransferase and aspartate aminotransferase in the blood; the tail fin pigment cell indicators include the number, aggregation state and red body color state of the tail fin pigment cells.

3. The fast, low-loss, effective cold stress evaluation system for red tilapia as claimed in claim 2, wherein: The L* value is lightness, which indicates the brightness or lightness of the color; the b* value is the yellow-blue axis, which indicates the position of the color on the yellow-blue spectrum axis.

4. The fast, low-loss, effective cold stress evaluation system for red tilapia as claimed in claim 1, wherein: The control group is red tilapia whose living water temperature is maintained at 20°C or above.

5. The fast, low-loss, effective cold stress evaluation system for red tilapia as claimed in claim 1, wherein: The steps of establishing the evaluation model include: S1. The body color index and blood index were compared with the corresponding indexes of the control group. If P < 0.05, it was considered to be significantly different and scored 1 point. Otherwise, it was considered to be non-significant and scored 0 point. S2. Quantify behavioral indicators and tail fin pigment cell indicators and record the scores; S3. Weight distribution: The weight coefficient of behavioral indicators is 0.3, the weight coefficient of body color indicators is 0.25, the weight coefficient of blood indicators is 0.3, and the weight coefficient of tail fin pigment cell indicators is 0.15; S4, get the formula 1 of the differentiation degree value, Differentiation degree value = (behavioral index score × 0.3 + body color index score × 0.25 + blood index score × 0.3 + tail fin pigment cell index score × 0.15) × 20.62 (Equation 1).

6. The fast, low-loss, and effective cold stress evaluation system for red tilapia as claimed in claim 5, wherein: Behavioral indicators are quantified in the following ways: Case 1: No abnormal behavior, judged as normal, 0 points; Case 2: Decreased food intake and slower swimming speed are considered mild abnormalities and are scored 1 point; Case 3: The fish has a significant decrease in food intake, sinks to the bottom and moves less, which is considered as moderate abnormality and is scored 2 points; Case 4: Stopping eating and losing body balance are considered severe abnormalities and are scored 3 points.

7. The rapid, low-loss, and effective cold stress evaluation system for red tilapia as claimed in claim 5, wherein: The quantification method of tail fin pigment cell index is: Case 1: Erythrocytes are not aggregated and are characteristically red, which is considered normal and scored 0 points; Case 2: Red pigment cells decrease and aggregate, red body color decreases, and melanocytes are absent. This is considered mild abnormality and is scored 1 point. Case 3: The red pigment cells decrease and aggregate, the red body color decreases, and melanocytes appear, which is considered moderate abnormality and scored 2 points; Case 4: The number of red pigment cells decreases and aggregates, the red body color fades, melanocytes appear and the black body color deepens. This is judged as a severe abnormality and is scored 3 points.

8. The rapid, low-loss, and effective cold stress evaluation system for red tilapia as claimed in claim 5, wherein: The breeding strategy is regulated based on the differentiation degree value, including: 0<differentiation degree value≤20, normal state, normal breeding; 20<Differentiation value≤50, indicating the occurrence of cold stress compensation period, the water temperature should be raised to 18℃ and vitamin C should be added to the feed; 50<differentiation value≤70, indicating cold stress problem, isolation and warming, and injection of dexamethasone; 70<differentiation value≤100, indicating acute cold stress problem, the red tilapia were transferred to a 25℃ recovery tank and injected with dexamethasone.

9. A rapid, low-loss, and effective cold stress evaluation method for red tilapia, characterized in that: The cold stress evaluation of red tilapia is performed using the evaluation system according to claim 1, wherein the specific steps are: A control group and a monitoring group were set up, and the behavioral indicators, body color indicators, blood indicators and tail fin pigment cell indicators of red tilapia in the control group and the monitoring group were measured respectively; The measured value of the control group was used as the standard value, and the evaluation model was used to judge the degree of differentiation between the monitoring group and the control group, and the differentiation degree value was calculated; According to the range of differentiation degree values, the status of red tilapia in the monitoring group is determined and the breeding strategy is adjusted.

10. The rapid, low-loss, and effective cold stress evaluation method for red tilapia as claimed in claim 9, wherein: The states of the red tilapia in the monitoring group include normal state, cold stress compensatory state, cold stress state and acute cold stress state.

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